JP2020046053A - Scissors gear - Google Patents

Abstract

To inhibit inclination of a sub gear.SOLUTION: A scissors gear includes: a main gear having a main teeth part at an outer periphery part; a sub gear 2 which is fitted in the main gear so as to enable relative rotation and has a sub teeth part 12 at an outer periphery part; a spring 8 which biases the sub gear to the main gear in a circumferential direction; a protrusion 40 formed at one end of the spring and protruding in a radial direction; and an engagement groove 41 which is formed at the sub gear and with which the protrusion is engaged. In a gear axis C direction, a width center of the protrusion and a width center of the sub teeth part are located at the same position.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to scissor gears.

  Among the gears, there is a scissors gear that removes backlash with a mating gear in order to reduce rattle noise due to rattling vibration. The scissor gear includes a main gear, a sub-gear fitted to the main gear so as to be rotatable relative to the main gear, and a spring for urging the sub-gear relative to the main gear in a circumferential direction. The backlash is removed by sandwiching the teeth of the mating gear with the teeth of the sub gear.

JP 2005-240842 A

  Generally, the spring is a C-shaped spring, one end of which is fixed to a main gear and locked to a main pin protruding toward the sub-gear. The other end of the spring is fixed to a sub-gear and locked to a sub-pin protruding toward the main gear.

  However, in the case of such a structure, the center of the load from the spring on the sub-pin is shifted and offset from the meshing center, ie, the center of the width of the teeth of the sub-gear, in the gear axis direction. For this reason, there is a problem in that a load is applied to the sub-gear to cause the sub-gear to tilt or fall with respect to the main gear, thereby promoting the inclination or fall of the sub-gear. Such inclination or inclination of the sub-gear may prevent proper transmission of torque, engagement with a mating gear, and increase noise, and therefore should be avoided as much as possible.

  Accordingly, the present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a scissor gear that can suppress the inclination of the sub gear.

According to one aspect of the present disclosure,
A main gear having main teeth on the outer periphery,
A sub-gear fitted to the main gear so as to be relatively rotatable and having a sub-tooth portion on an outer peripheral portion;
A spring that urges the sub-gear in the circumferential direction with respect to the main gear;
A projection formed at one end of the spring and projecting in a radial direction;
An engagement groove formed in the sub-gear and engaging the projection;
With
A scissors gear is provided in which the width center of the protrusion and the width center of the sub-tooth portion are located at the same position in the gear axis direction.

  Preferably, in the gear axis direction, the width of the projection and the width of the sub-tooth portion are made equal.

  Preferably, the sub gear has an accommodation groove for accommodating the spring.

  Preferably, the protrusion protrudes radially outward.

  Preferably, the spring is a C-shaped spring, and the entirety including the protrusion has a constant width in the gear axis direction.

  According to the present disclosure, the inclination of the sub gear can be suppressed.

1 is a front view of a scissors gear according to an embodiment of the present disclosure. FIG. 2 is a longitudinal sectional side view of the scissors gear, and is a sectional view taken along line II-II of FIG. 1. FIG. 9 is a rear view showing a state when the sub gear in which the spring is arranged in the accommodation groove is viewed from the rear. FIG. 4 is a sectional view taken along line IV-IV of FIG. 3.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

  FIG. 1 is a front view of a scissors gear according to the embodiment of the present disclosure. FIG. 2 is a vertical sectional side view of the scissor gear, and is a sectional view taken along line II-II of FIG. The scissor gear G includes a main gear 1 and a sub gear 2, and a combination of these two gears 1 and 2 constitutes one scissor gear G, that is, a gear assembly. C indicates a central axis (referred to as a gear axis) of the scissors gear G. Hereinafter, unless otherwise specified, the axial direction, the radial direction, and the circumferential direction refer to the axial direction, the radial direction, and the circumferential direction with reference to the gear shaft C. For convenience, the right side of FIG. 2 is referred to as an axial front, and the left side of FIG. 2 is referred to as an axial rear. FIG. 1 is a front view when viewed from the front in the axial direction.

  The scissors gear G is configured as a helical gear having outer peripheral teeth, and is applied so as to mesh with a mating gear (not shown). The scissor gear G may be configured as another type of gear, for example, a spur gear.

  The main gear 1 and the sub gear 2 are arranged adjacent to each other in the axial direction, and the sub gear 2 is arranged adjacent to the front of the main gear 1 in the axial direction.

  The main gear 1 and the sub gear 2 each have a main tooth portion 11 and a sub tooth portion 12 on the outer peripheral portion. The main tooth portion 11 and the sub tooth portion 12 have the same module, number of teeth, and tooth shape. The main teeth 11 and the sub teeth 12 are formed as if the teeth of one gear were divided in the thickness direction. Both the main teeth 11 and the sub teeth 12 are meshed with the mating gear. The sub gear 2 is mainly used for removing backlash, and is not actively used for transmitting driving force. Therefore, the tooth width of the sub-tooth portion 12 is made smaller than the tooth width of the main gear 1.

  The main gear 1 integrally has a cylindrical boss 10 on an inner peripheral portion thereof. On the other hand, the sub-gear 2 is integrally formed generally in a ring plate shape, and has a fitting hole 5 on an inner peripheral portion thereof. By fitting the fitting hole 5 to the gear fitting surface 4 formed on the outer peripheral portion of the boss 10, the sub gear 2 is fitted to the boss 10 so as to be relatively rotatable and coaxial.

  In order to position the sub-gear 2 in the axial direction with respect to the main gear 1, a C-shaped snap ring 32 that can be expanded and contracted is fitted and attached to a ring groove 31 formed in the gear fitting surface 4.

  A shaft hole 11A is provided in the inner peripheral portion of the boss 10, and a shaft (not shown) is inserted into the shaft hole 11A. In the present embodiment, the cylindrical slide bearing 3 is fixed to the shaft hole 11A by press fitting, and the scissors gear G is rotatably and coaxially supported by the shaft by fitting the slide bearing 3 to the shaft. The sliding bearing 3 is integrally attached to the main gear 1 and forms a part of the main gear 1.

  However, the sliding bearing 3 may be fitted into the shaft hole 11A so as to be relatively rotatable. Further, the slide bearing 3 may be omitted and the shaft hole 11A may be directly fitted to the shaft. The main gear 1 may be fitted and fixed to a rotatable shaft.

  A spring chamber 7 is formed between the main gear 1 and the sub gear 2, and a spring 8 for urging the sub gear 2 in the circumferential direction with respect to the main gear 1 is arranged in the spring chamber 7. The spring chamber 7 is formed by an axial gap between a ring-shaped accommodation groove 9 formed on the rear surface of the sub gear 2 and accommodating the spring 8 and the front surface of the main gear 2. The spring 8 is a C-shaped spring that makes one round in the circumferential direction, and one end and the other end of the spring 8 are locked by the main gear 1 and the sub gear 2, respectively. This will be described in detail later.

  In a state where the spring 8 is disposed in the spring chamber 7 and the sub gear 2 is simply assembled to the main gear 1, the phases of the main gear 1 (main tooth portion 11) and the sub gear 2 (sub tooth portion 12) are out of phase. The gear cannot be engaged. In order to mesh with the mating gear, the main gear 1 and the sub gear 2 must be twisted against each other against the urging force of the spring 8, push the spring 8 open, and make them have the same phase.

  In order to keep the main gear 1 and the sub gear 2 in the same phase, the scissors gear G is provided with a fixing bolt 17. The fixing bolt 17 is inserted from the front into an insertion hole 18 provided in the sub gear 2, and is screwed and screwed into a screw hole 19 provided in the main gear 1. Of course, the insertion hole 18 and the screw hole 19 are coaxial when the main gear 1 and the sub gear 2 have the same phase. By maintaining the main gear 1 and the sub gear 2 in the same phase in this manner, the scissors gear G can be easily meshed with the mating gear.

  After the engagement, the fixing bolt 17 is removed. As a result, the spring 8 contracts, and the teeth of the main gear 1 and the teeth of the sub gear 2 sandwich the teeth of the mating gear, thereby eliminating backlash. Further, rattle noise due to rattling vibration can be reduced.

  FIG. 3 shows a state when the sub gear 2 in which the spring 8 is disposed in the accommodation groove 9 is viewed from the rear. FIG. 3 also shows a main pin 13 fixed to the main gear 1 and protruding forward toward the sub gear 2. FIG. 4 is a sectional view taken along line IV-IV of FIG.

  As shown in the figure, the spring 8 is a C-shaped spring that makes one round in the circumferential direction, and one end in the longitudinal direction is locked to the main pin 13. That is, a semicircular concave seat 15 is formed at one end, and the concave seat 15 is seated on the cylindrical main pin 13, so that one end of the spring 8 is engaged with the main pin 13, and thus the main gear 1. Is stopped.

  On the other hand, at the other end in the longitudinal direction of the spring 8 (corresponding to one end in the claims), a projection 40 projecting in the radial direction is formed. In the case of the present embodiment, the projection 40 projects outward in the radial direction. The sub gear 2 has an engagement groove 41 with which the projection 40 is engaged. The engagement groove 41 extends radially outward from the outer peripheral surface of the accommodation groove 9 and communicates with the accommodation groove 9. The other end of the spring 8 is locked to the sub gear 2 by engaging or inserting the projection 40 into the engagement groove 41.

  The spring 8 as a whole including the protrusion 40 has a constant width W1 in the axial direction. That is, the axial width of the projection 40 is equal to the axial width of the main body portion 42 of the spring 8 excluding the projection 40 portion. The radial width W2 of the main body portion 42 of the spring 8 is also constant. The protrusion 40 is formed integrally with the spring 8 and is formed integrally with the main body portion 42. The spring 8 is formed integrally by, for example, stamping a plate made of spring steel by press working. The projection 40 is entirely inserted into the engagement groove 41 in the width W1 direction.

  Here, as shown in FIG. 4, in the axial direction (the left-right direction in FIG. 4), the width center C1 of the protrusion 40 (that is, the width center of the spring) and the width center C2 of the sub-tooth portion 12 are located at the same position. Is done. Further, in the axial direction, the width W1 of the projection 40 (that is, the width of the spring) is equal to the width W2 of the sub-tooth portion 12.

  When the spring 8 is in contact with the rearwardly facing bottom surface 43 of the housing groove 9, the axial direction of the bottom surface 43 is set so that the width center C1 of the protrusion 40 and the width center C2 of the sub-tooth portion 12 are located at the same position. The position has been set. Therefore, it is possible to maintain both width centers C1 and C2 at the same position as much as possible. On the rear surface of the sub gear 2, a sliding contact surface 44 that slides on the front surface of the main gear 1 is formed. The sliding contact surface 44 is located slightly behind the rear end of the sub-tooth portion 12. Further, the sliding contact surface 44 is located slightly behind the rear end of the spring 8 in contact with the bottom surface 43 of the accommodation groove 9. The sliding contact surface 44 is located radially inward of the sub-tooth portion 12 and radially outward of the accommodation groove 9. The engagement groove 41 is formed in the sliding contact surface 44.

  Next, the operation and effect of the present embodiment will be described.

  When the scissors gear G is used, a rotational load is applied to the sub-tooth portion 12 of the sub-gear 2 from the tooth portion of the mating gear that meshes with the sub-tooth portion 12. The center of the load in the axial direction, that is, the load center, coincides with the width center C2 of the sub-tooth portion 12.

  A load in the rotation direction is applied to the inner wall of the engagement groove 41 in the sub gear 2 from the projection 40 of the spring 8. The center of the load in the axial direction, that is, the center of the load, matches the width center C1 of the protrusion 40.

  In the case of the present embodiment, the width center C1 of the protrusion 40 is located at the same position as the width center C2 of the sub-tooth portion 12. Therefore, there is no axial displacement between the two width centers C1 and C2, that is, the load centers, and there is no offset.

  For this reason, a load (called a tilting load) caused by a spring load, which tends to tilt or tilt the sub gear 2 with respect to the main gear 1, can be suppressed from acting on the sub gear 2. Therefore, the inclination of the sub gear 2 with respect to the main gear 1 can be suppressed. Also, various problems caused by the inclination of the sub gear 2 can be solved.

  In the present embodiment, the width W1 of the projection 40 is equal to the width W2 of the sub-tooth portion 12. By doing so, the axial position of the axial region where the sub gear 2 receives the load from the projection 40 can be made equal to the axial position of the axial region where the sub gear 2 receives the load from the mating gear. Therefore, it is possible to further suppress the tilting load from acting on the sub-gear 2 and further suppress the inclination of the sub-gear 2.

  Although the embodiments of the present disclosure have been described above in detail, various other embodiments of the present disclosure are also conceivable.

  (1) For example, the projection of the spring may be projected inward in the radial direction. Correspondingly, the engagement groove may also be formed to extend radially inward from the inner peripheral surface of the accommodation groove.

  (2) The width of the projection in the axial direction may be different from the width of the sub-tooth portion, or may be different from the width of the main body of the spring.

  (3) The projection may not be formed integrally with the spring, but may be formed separately.

  The embodiments of the present disclosure are not limited to the above-described embodiments, but include all modifications, applications, and equivalents included in the spirit of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as limiting, but can be applied to any other technology belonging to the scope of the idea of the present disclosure.

G Scissors gear 1 Main gear 2 Sub gear 8 Spring 9 Housing groove 11 Main tooth part 12 Sub tooth part 40 Projection 41 Engagement groove C Gear shaft

Claims (5)

A main gear having main teeth on the outer periphery,
A sub-gear fitted to the main gear so as to be relatively rotatable and having a sub-tooth portion on an outer peripheral portion;
A spring that urges the sub-gear in the circumferential direction with respect to the main gear;
A projection formed at one end of the spring and projecting in a radial direction;
An engagement groove formed in the sub-gear and engaging the projection;
With
A scissors gear wherein the width center of the protrusion and the width center of the sub-tooth portion are located at the same position in the gear axis direction. The scissors gear according to claim 1, wherein a width of the projection is equal to a width of the sub-tooth portion in the gear axis direction. 3. The scissors gear according to claim 1, wherein the sub gear has a receiving groove for receiving the spring. 4. The scissors gear according to any one of claims 1 to 3, wherein the protrusion projects radially outward. The scissors gear according to any one of claims 1 to 4, wherein the spring is a C-shaped spring, and the entirety including the protrusion has a constant width in the gear axis direction.

Images